The Hundred Years War is a conflict that stands out by virtue of its length -- and yet in one sense, it is only one episode in the longstanding struggle between England and France during the Middle Ages. From the moment Duke William the Bastard of Normandy defeated Harold Godwinson at the Battle of Hastings and became King William I of England, England and France were intertwined by the complex ties of feudalism, with the ruler of England also a vassal of the French monarch. As the power of the French crown grew, this complicated relationship led to increasing conflict, of which the Hundred Years War represented its culmination.

That Johnathan Sumption spends nearly a third of his book recounting the tangled events that led to the start of the conflict in 1337 is in part a reflection of this. It also embodies, though, the patient, detailed recounting of a conflict that was epic in both scope and length. In this, the first of his multi-volume history of the war, he details the development of the war from its origins in the inter-kingdom politics of 14th century England and France to the English victory at Crécy and its successful siege of Calais a decade later. This is less straightforward than it may appear on the surface, as more than England and France were involved in the conflict. In one sense, the war emerged out of England's ongoing conflict with it's Scottish neighbor to the north, which France sought to exploit in its ongoing pursuit of the English crown's holdings in Gascony. As war loomed England's king Edward III sought out allies from throughout northwestern Europe, whose support he gained primarily through generous subsidies, which were financed in large measure using extraordinary loans from Italian banking houses. As Sumption demonstrates, the financial aspects of the war were central to the conflict, often playing a more decisive role in developments than events on the battlefield.

One of the reasons for the centrality of finance was the scope of the conflict, which extended from Scotland to southwestern France and encompassed both land and naval conflict. Yet the governments of the era lacked the resources to fight wars on such a vast scale, which often led what a modern age would term outsourcing, with both sides relying upon third parties such as regional nobles to advance their interests, Usually these people were more interested in profit than in strategy and politics, yet even their mercenary goals could serve the interests of their employers by tying down enemy troops, even if it came at the cost of innumerable suffering for the inhabitants of the regions where the forces were engaged.

Much of Sumption's account is devoted to recounting these side struggles, which defined the experience of the war for most of its participants and victims. Yet for all of its complexity and detail (a level that might turn off some readers) Sumption's narrative never sags from it. This in itself makes Sumption's book a considerable achievement, one that once its subsequent volumes (of which there are two, with a third coming out this fall) are completed will likely stand as the definitive account of this epic struggle for decades to come.